1. Field of the Invention
The present invention relates to automobile radiators and engines and preventing corrosion in the cooling system especially those with components of dissimilar metal construction. (Engines with alumina heads and iron blocks and steel radiators, engines of all aluminum construction with steel radiators and engines of iron construction with radiators of aluminum construction.) It is these types of combinations that present the most problems regarding cooling system corrosion.
2. Description of Related Art
Automobile cooling systems use water and coolant/antifreeze liquids circulated through the water jackets of the engine, heads and water pump to effect heat transfer. Then the hot liquid is piped back to the radiator/storage tank which is a liquid to air heat exchanger. A typical radiator is made up of a storage tank either above or to the side of the cooling tubes and exchanged cooling fins. This storage tank has an opening to the interior of the storage tank part, a core of cooling tubes which is where the coolant liquid flows and connected to these cooling tubes are fins which transfer heat to the air which is pulled or pushed through the fins and around the tubes for heat transfer from the coolant to the air passing through.
Radiators and engines were historically made of iron and steel which as similar metals had little corrosion caused by electrolytic activity. Any engine/head/radiator combination of dissimilar metals is very vulnerable to corrosion because of this electrolytic activity. In such cases the aluminum components corrode and become porous and may begin to leak in as little as 12 to 24 months.
It is the electrolytic activity, where one of the metals act as an anode and corrodes and other metals act as a cathode and do not corrode. Consequently, corrosion inhibitors have been developed to prevent corrosion. Chemical corrosion inhibitors can inhibit electrolysis, but are toxic, present problems to the environment and problems of disposal.
Sacrificial anodes, constructed of magnesium, aluminum, zinc or combinations thereof have also been used as corrosion inhibitors. U.S. Pat. No. 5,292,595 describes a sacrificial anode of specified composition bonded to the core metal to prevent the occurrence of pitting corrosion of core material in a heat exchanger such as a radiator or heater core.
Unfortunately such an anode is hard to access to check its condition or replace it when it wears out. A need exists for a corrosion inhibiting sacrificial anode which is easily accessible. Since a sacrificial anode is designed to be consumed, easy accessibility would allow verification of its effective working status and efficient replacement when depleted.